From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from gateway20.websitewelcome.com ([192.185.55.25]:19068 "EHLO gateway20.websitewelcome.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753097AbeEURpt (ORCPT ); Mon, 21 May 2018 13:45:49 -0400 Received: from cm10.websitewelcome.com (cm10.websitewelcome.com [100.42.49.4]) by gateway20.websitewelcome.com (Postfix) with ESMTP id 3F7F1400F061B for ; Mon, 21 May 2018 11:57:19 -0500 (CDT) Date: Mon, 21 May 2018 11:57:17 -0500 From: "Gustavo A. R. Silva" To: Hans Verkuil , Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH] media: si470x: fix potential Spectre variant 1 Message-ID: <20180521165717.GA9167@embeddedor.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-media-owner@vger.kernel.org List-ID: band->index can be controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: drivers/media/radio/si470x/radio-si470x-common.c:758 si470x_vidioc_enum_freq_bands() warn: potential spectre issue 'bands' Fix this by sanitizing band->index before using it to index `bands' Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Cc: stable@vger.kernel.org Signed-off-by: Gustavo A. R. Silva --- drivers/media/radio/si470x/radio-si470x-common.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/media/radio/si470x/radio-si470x-common.c b/drivers/media/radio/si470x/radio-si470x-common.c index c40e175..e81f9aa 100644 --- a/drivers/media/radio/si470x/radio-si470x-common.c +++ b/drivers/media/radio/si470x/radio-si470x-common.c @@ -110,6 +110,10 @@ /* kernel includes */ #include "radio-si470x.h" +/* Hardening for Spectre-v1 */ +#include + + /************************************************************************** * Module Parameters **************************************************************************/ @@ -755,7 +759,7 @@ static int si470x_vidioc_enum_freq_bands(struct file *file, void *priv, return -EINVAL; if (band->index >= ARRAY_SIZE(bands)) return -EINVAL; - *band = bands[band->index]; + *band = bands[array_index_nospec(band->index, ARRAY_SIZE(bands))]; return 0; } -- 2.7.4